JPH0885445A - Booster - Google Patents

Abstract

PURPOSE: To reduce the input when the operation of a booster is started and improve the responsiveness at the time of operation by providing a valve mechanism, which forms a pressure chamber facing the end face on the rear side of a valve plunger, allows the pressure chamber to communicate with a variable-pressure chamber or a constant-pressure chamber during the nonoperational period, and allows the pressure chamber to communicate with the atmospheric air at the time of operation. CONSTITUTION: This booster is provided with the first valve mechanism 15 switching the communication state between a constant-pressure chamber, a variable-pressure chamber, and the atmospheric air in conjunction with an input shaft 32. A step end face 17a is formed on the rear side of the valve plunger 17 of the first valve mechanism 15. A guide section 5a expanded inward in the radial direction is formed on the inner periphery of a valve body 5, and a pressure chamber 36 is formed between the guide section 5a and the step end face 17a. The first seat section 32a is formed on the rear side end face of a large-diameter section 32A at the tip of the input shaft 32 as the second atmospheric valve 38 opening or closing a communication path 17d, the second seat section 32b is formed on the shaft section at the tip of the input shaft 32 as a vacuum valve 43 opening or closing an orifice passage 41, and the second valve mechanism 37 is formed with both valves 38, 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a booster used for automobile brakes, and more particularly to improvement of a valve mechanism of the booster.

[0002]

2. Description of the Related Art Conventionally, as a booster, a cylindrical valve body slidably provided in a shell, a power piston provided in the valve body, a constant pressure chamber and a transformer formed in front of and behind the power piston. A chamber and a first valve mechanism that is interlocked with the input shaft and switches the communication state of the fluid passage between the constant pressure chamber, the variable pressure chamber, and the atmosphere, and the first valve mechanism is formed on the inner peripheral surface of the valve body. It is known that a first valve seat, a valve plunger slidably fitted to the valve body, a second valve seat formed on the valve plunger, and a valve body that comes in contact with and separates from the both valve seats are known. ing. In the conventional booster described above, in the non-actuated state, the valve body is separated from the first valve seat, while the valve body is seated on the second valve seat. Therefore, when the booster is not in operation, the front side of the valve element has a negative pressure and the rear side has an atmospheric pressure, and the valve element is biased toward the front side by the differential pressure before and after that. . Then, conventionally, in order to cancel the biasing force due to the differential pressure and stop the input shaft and the valve plunger at the non-operating position, a return spring is mounted over the valve body and the input shaft.

[0003]

By the way, in such a conventional booster, in order to improve the responsiveness at the time of operation, the second valve seat and the seat portion of the valve body with which the second valve seat comes in contact with and separates from each other are used. It may be desired to expand the constructed atmospheric valve. However, when the atmospheric valve of the booster is expanded in diameter, the differential pressure acting on the valve element in the non-actuated state described above increases, and the set load of the return spring described above also needs to increase accordingly. When the set load of the return spring is increased in this way, there is a disadvantage that the input (pedal force) of the input shaft when operating the booster increases. Therefore, an object of the present invention is to reduce the input of the input shaft at the start of operation of the booster and at the same time improve the responsiveness at the time of operation.

[0004]

That is, according to the present invention, a cylindrical valve body slidably provided in a shell, a power piston provided in the valve body, and a constant pressure section formed before and after the power piston are provided. Chamber and a variable pressure chamber, and a first valve mechanism that switches a communication state of a fluid passage between the constant pressure chamber and the variable pressure chamber and the atmosphere in association with the input shaft, and the first valve mechanism is provided on the inner peripheral surface of the valve body. Formed on the first
A booster including a valve seat, a valve plunger slidably fitted in the valve body, a second valve seat formed in the valve plunger, and a valve element that comes in contact with and separates from the valve seats. A pressure chamber facing the rear-side end face of the valve plunger is formed and is opened / closed in conjunction with the input shaft. When not in operation, the pressure chamber communicates with the variable pressure chamber or constant pressure chamber, and when in operation, communicates with the atmosphere. The second valve mechanism is provided.

[0005]

With this structure, when the booster is not operating, the valve element is seated on the second valve seat while being separated from the first valve seat, so that the constant pressure chamber and the variable pressure chamber communicate with each other. On the other hand, the communication between the variable pressure chamber and the atmosphere is cut off. Further, the second valve mechanism introduces a negative pressure from the variable pressure chamber (constant pressure chamber) into the pressure chamber. When the brake pedal is stepped on from the non-operation of the booster, the atmosphere is introduced into the pressure chamber by the second valve mechanism, so that the valve plunger is in the operating direction due to the pressure of the atmosphere in the pressure chamber. It is advanced toward the side. As a result, the valve body separates from the second valve seat while seating on the first valve seat, so that the communication between the variable pressure chamber and the constant pressure chamber is blocked, and at the same time, the atmosphere is introduced into the variable pressure chamber,
A booster is activated as is well known in the art. in this way,
When operating the booster, the valve plunger is moved forward by the pressure of the atmosphere introduced into the pressure chamber, so that the input of the input shaft at the start of operation of the booster may be a small input. Therefore, in order to improve the responsiveness of the booster during operation, the diameter of the atmosphere valve constituted by the second valve seat and the seat portion of the valve body that comes in contact with and separates from the second valve seat is expanded to deactivate the valve plunger and the input shaft. Even if the set load of the return spring that is kept in the position becomes large, the input of the input shaft at the start of operation may be small. Therefore, the input of the input shaft at the time of starting the operation can be reduced, and the responsiveness at the time of the operation can be improved.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In FIG. 1, the inside of the shell 1 is divided into a front chamber 3 and a rear chamber 4 in front of and behind by a center plate 2 provided at the center. A substantially cylindrical valve body 5 is slidably pierced through the shaft portions of the shell 1 and the center plate 2 while being kept airtight by annular seal members 6 and 7, respectively. A front power piston 11 and a rear power piston 12 housed in the front chamber 3 and the rear chamber 4 are connected to the valve body 5, respectively, and a front diaphragm 13 and a rear diaphragm 14 are provided on the back surfaces of the power pistons 11 and 12, respectively. And a constant pressure chamber A and a variable pressure chamber B are formed in front and rear of the front diaphragm 13, and a constant pressure chamber C and a variable pressure chamber D are also formed in front and rear of the rear diaphragm 14, respectively. A first valve mechanism 15 for switching a fluid circuit between the two constant pressure chambers A and C and the two variable pressure chambers B and D is provided in the valve body 5, and the first valve mechanism 15 is provided in the valve body 5. An annular first valve seat 16 formed on the inner peripheral surface and the annular first valve seat 16
The annular second valve seat 18 formed on the valve plunger 17 which is slidably provided on the valve body 5 on the inner side of the valve body 5 and the two valve seats 16 and 18 from the right side of FIG. 1 by the elastic force of the spring 21. And a valve element 22 to be seated. The first
The valve seat 16 and the seat portion of the valve body 22 that comes in contact with and separates from the valve seat 16 constitute a first vacuum valve 23.
The space on the outer side is communicated with the constant pressure chamber A and the constant pressure chamber C via a constant pressure passage 24 formed in the valve body 5, and the constant pressure chamber A is connected to the intake manifold of the engine via a negative pressure introducing pipe (not shown). It is in communication. Further, the second valve seat 18 and the seat portion of the valve body 22 which is brought into contact with and separated from the second valve seat 18 constitute a first atmosphere valve 25, and a space 19 in an intermediate portion between the first atmosphere valve 25 and the first vacuum valve 23. Is
The variable pressure chamber D is communicated with the variable pressure chamber 26 through the radial variable pressure passage 26 formed in the valve body 5, and the variable pressure chamber D is communicated with the variable pressure chamber B through the axial variable pressure passage 27 formed in the valve body 5. Further, the space inside the first atmosphere valve 25 is communicated with the atmosphere as a pressure fluid source through a pressure passage 28 formed in the valve body 5, and a filter 31 is provided in the pressure passage 28. ing. As will be described later in detail, a tip end portion of the input shaft 32 is inserted and interlocked with a rear shaft portion of the valve plunger 17, and a terminal end portion of the input shaft 32 is connected to a brake pedal (not shown). On the other hand, a reaction disc 33 is arranged on the front side of the valve plunger 17, and the reaction disc 33 is fitted to the right end portion of the push rod 34. The left end portion of the push rod 34 is slidably projected to the outside from the shaft portion of the front shell 1 via a seal member, and is interlocked with a piston of a master cylinder (not shown). Further, the valve body 5 is normally held in the inoperative position in the drawing by a return spring 35. However, as shown in an enlarged manner in FIG. 2, in the present embodiment, the pressure chamber 36 is formed between the valve body 5 and the valve plunger 17, and the second valve mechanism 37 is provided in the valve plunger 17 to start the operation. The input of the input shaft 32 at the time is reduced. That is, the valve plunger 17 of this embodiment has a stepped end face 17a facing the rear side at a required axial position,
A guide portion 5a that bulges radially inward is formed on the inner peripheral portion of the valve body 5 so as to face the step end surface 17a. The step end surface 17a of the valve plunger 17
Between the pressure chamber 3 and the end surface of the guide portion 5a facing the pressure chamber 3
6 are partitioned and formed. The valve plunger 17 has a larger diameter on the rear side than the guide portion 5a.
The second valve seat 18 is formed on the rear end surface of the large-diameter portion 17b. Also, the valve plunger 17
The portion on the rear side of the large-diameter portion 17b of the valve plunger 17 penetrates the first atmospheric valve 25 and is interposed on the inner side of the valve body 22, and the end 17c on the rear side of the valve plunger 17 has a larger diameter. And two large and small steps are formed. In the shaft portion of the valve plunger 17 on the rear side of the step end surface 17a,
A communication passage 17d formed of a stepped hole in the axial direction is formed,
The front end of the communication passage 17d has the pressure chamber 36
The end of the communication passage 17d on the rear side is opened to the pressure passage 28. The large diameter portion 17b
The communication passage 17d on the inner side of is a large-diameter hole 17e, and the inside of the communication passage 17d on the rear side of the position of the large-diameter hole 17e has a slightly smaller inner diameter than the large-diameter hole 17e. In addition, the inside of the communication passage 17d located on the front side of the large diameter portion 17b has the smallest inner diameter and is provided at a position slightly displaced from the shaft portion in the radial direction. Then, the front side portion of the input shaft 32 is inserted into the large diameter hole 17e and the rear side thereof and the communication passage 17d, and the large diameter portion 32A located at the tip of the input shaft 32 is interposed in the large diameter hole 17e. I am letting you. A first seat portion 32a made of an annular protrusion is formed on the rear end surface of the large diameter portion 32A, and the first seat portion 32a and the large diameter hole 1 facing the first seat portion 32a are formed.
A second atmospheric valve 38 that opens and closes the communication passage 17d is formed by the end surface of 7e. Further, an orifice passage 41 having a small inner diameter is formed at a position on the front side that is continuous from the large diameter hole 17e, and the orifice passage 41 connects the large diameter hole 17e (communication passage 17d) to the outside of the valve plunger 17. It communicates with the space 19. The shaft portion at the tip of the input shaft 32, which faces the opening portion on the inner side of the orifice passage 41 opening to the large diameter hole 17e, is the second seat portion 32b formed of a protrusion matching the shape of the opening portion. The second seat portion 32b and the opening on the inner side of the orifice passage 41 facing the second seat portion 32b constitute a second vacuum valve 43 that opens and closes the orifice passage 41. A spring 44 having a small set load is mounted between the front side of the second seat portion 32b at the tip of the input shaft 32 and the front side end surface of the large diameter hole 17e. It is biased to the rear side with respect to 17. Therefore, in the non-operating state in which the brake pedal is not depressed, as shown in FIG. 2, the second atmospheric valve 38 is closed and the second vacuum valve 43 is opened. Therefore, at this time, the orifice passage 41 and the large diameter hole 1
Negative pressure is introduced into the pressure chamber 36 via the communication passage 17d on the front side of 7e. further,
In this embodiment, the valve body 22 of the first valve mechanism 15 is replaced by the double valve seat 1
The springs 21 to be seated on the valves 6 and 18 are elastically mounted over the back surface of the seat portion of the valve body 22 and the step portion on the rear side of the valve plunger 17. In addition, the valve plunger 17 and the input shaft 3
The spring 45 that returns the valve 2 to the inoperative position shown in FIG.
The base is fixedly attached to the valve body 5 and the retainer 46 is mounted over the step portion on the rear side of the valve plunger 17. The retainer 46 in this embodiment substantially constitutes a part of the valve body 5. In the above configuration, when the brake booster is in the non-operating state,
As shown in, the first vacuum valve 23 is open, the first atmospheric valve 25 is closed, and the second vacuum valve 43 is open, while the second atmospheric valve 38 is closed. for that reason,
Negative pressure is introduced not only in the constant pressure chambers A and C but also in the variable pressure chambers B and D, and also in the pressure chamber 36. When the brake pedal is depressed from this non-operating state, the input shaft 32 connected to the brake pedal is advanced against the spring 44, so that the second atmospheric valve 38 is opened and the second vacuum valve 43 is closed. To be done. As a result, the orifice passage 41 is closed and the communication passage 17d is opened, so that the atmosphere in the pressure passage 28 is introduced into the pressure chamber 36 via the communication passage 17d. In this way, the pressure chamber 36
When the atmosphere is introduced into the inside, the pressure of the atmosphere in the pressure chamber 36 urges the valve plunger 17 toward the front side, so that the valve plunger 17 is advanced against the spring 45. As a result, the first vacuum valve 23 is closed while the first atmospheric valve 25 is opened, and the constant pressure chambers A and C and the variable pressure chambers B and
Since the communication with D is blocked and the atmosphere is introduced into the variable pressure chambers B and D, the brake booster is operated as conventionally known. In this way, in this embodiment, when the brake booster is operated, the spring 45 can be compressed by the pressure of the atmosphere in the pressure chamber 36, so the input of the input shaft 32 at the start of the operation is the spring. It only requires a small input to compress 44. Therefore, in order to improve the response when the brake booster operates, the first atmospheric valve 25
Even if the diameter of is increased and the set load of the spring 45 increases accordingly, the input of the input shaft 32 at the start of operation does not increase. Therefore, according to the present embodiment, it is possible to improve the responsiveness during the operation without increasing the input of the input shaft 32 at the start of the operation of the brake booster. In contrast to this embodiment, in the conventional booster shown in FIG. 3, the pressure chamber 3 in this embodiment is
6 and the second valve mechanism 37 are not provided, and the valve plunger 17 and the input shaft 32 are directly connected. Then, the valve plunger 17 and the input shaft 3
The spring 45 for returning the 2 and the non-operating position is elastically mounted over the valve body 5 and the input shaft 32. In such a conventional configuration, if the diameter of the first atmospheric valve 25 is increased in order to improve the response during operation,
In the non-actuated state, the differential pressure that biases the valve element 22 toward the front side increases, and accordingly, it becomes necessary to increase the set load of the spring 45. It has been pointed out that when the set load of the spring 45 is increased in this way, the input of the input shaft 32 at the start of operation is increased. Although the above embodiments have described the case where the present invention is applied to the tandem brake booster, the present invention can also be applied to a single type or triple type brake booster.

[0007]

As described above, according to the present invention, it is possible to reduce the input of the input shaft at the start of operation and to improve the responsiveness at the time of operation.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a sectional view showing a conventional technique.

[Description of sign]

5 ... Valve body 11 ... Front power piston 12 ... Rear power piston 15 ... First valve mechanism 16 ... First valve seat 17 ... Valve plunger 17a ... End face 18 ... Second valve seat 36 ... Pressure chamber 37 ... Second valve mechanism A, C ... Constant pressure room B, D ... Transformer room

Claims (2)

[Claims] 1. A tubular valve body slidably provided in a shell, a power piston provided in this valve body, a constant pressure chamber and a variable pressure chamber defined in front of and behind the power piston, and interlocked with an input shaft. A first valve mechanism for switching the communication state of the fluid passage between the constant pressure chamber, the variable pressure chamber, and the atmosphere, the first valve mechanism having the first valve seat formed on the inner peripheral surface of the valve body; A booster comprising a valve plunger slidably fitted in a valve body, a second valve seat formed in the valve plunger, and a valve element that comes into contact with and separates from the valve seats, wherein a rear side of the valve plunger is provided. A second valve mechanism that forms a pressure chamber facing the end face that faces, is opened and closed in conjunction with the input shaft, communicates the pressure chamber with the variable pressure chamber or the constant pressure chamber when not operating, and communicates with the atmosphere when operating. That it was established Booster and butterflies. 2. A communication passage, one end of which communicates with the pressure chamber and the other end of which communicates with the atmosphere, is formed in a rear shaft portion of the valve plunger, and an input shaft is inserted into the communication passage from the rear side. The first formed with the rear side facing the tip of this input shaft
A second atmosphere valve for opening and closing the communication passage is formed by the seat portion and the end surface facing the front side of the communication passage opposite to the seat portion;
An orifice passage is formed in the valve plunger for communicating the inside of the communication passage located on the front side of the second atmosphere valve with the variable pressure chamber through the space portion on the outer side of the valve plunger,
A second vacuum valve for opening and closing the orifice passage is formed by a second seat portion formed with the front side facing the front end portion of the input shaft and an opening portion of the orifice passage facing the second seat portion,
Further, a spring for urging the input shaft toward the non-actuated position is elastically mounted across the input shaft and the valve plunger, and further, the second
The booster according to claim 1, wherein the second valve mechanism is constituted by an atmosphere valve and a second vacuum valve.